Valve and assembly for axially movable members

ABSTRACT

The fluid flow check valve uses a flexure plate or plates to accommodate the valve disk&#39;s axial motion required to open and close the valve. The flexure plate also limits the disk&#39;s motion in any lateral direction, so the valve disk will align properly with the valve seat and seal when it closes. The flexure plate is a flat, axial spring, made by cutting or otherwise manufacturing spiral cuts in a round, sheet metal disk. Valve qualities such as closing force, size and rigidity to lateral disk motion can be modified by varying the number and configuration of the plates, and by modifying plate characteristics. The compactness of the flexural plate design allows for a shorter valve length and cost as well as increased opportunity for flow optimisation.

FIELD OF THE INVENTION

[0001] This invention relates to axially movable members, and inparticular to valves and in particular nozzle-style check valves.

BACKGROUND OF THE INVENTION

[0002] In a conventional nozzle-style check valve, valve closure isspring assisted. When the flow decelerates the springs pushes a circulardisk into the valve seat preventing reverse flow and valve slam. Normalflow pushes the disc backwards and fully opens the valve. In this typeof design, flow accelerates in the seat area around the valve seat,enabling valve opening while locally lowering the static reducingpressure. The annular diffuser is subsequently used to gradually recoverthis pressure with minimum losses.

[0003] The circular disk is mounted on a shaft, which in turn is mountedin a bearing or bearings. These bearings are mounted in the shaftguidance. The bearings permit the axial movement of the disk, whilelimiting lateral disk movement. The disk will therefore align with thevalve seat and seal properly when closing. An axial compression springassists in closing the valve.

[0004] Disadvantages with this conventional check valve include bearingfriction (which increases due to contamination), reducing the effectivespring force and decreasing the valve's dynamic response, the length ofthe valve body necessary to house the shaft and bearings, and cost ofthe shaft-bearing-shaft guidance assembly.

SUMMARY OF THE INVENTION

[0005] This invention seeks to overcome problems with the prior art.

[0006] Therefore, according to a first aspect of the invention, there isprovided a valve, comprising a valve body defining a fluid passageway,with a valve seat in the fluid passageway, a valve disk support mountedwithin the valve body, a front flexure plate mounted on the valve disksupport, a valve disk secured to the front flexure plate and disposedwithin the valve body, the valve disk having a front side and a backside, the valve disk being movable axially within the valve body, thevalve being closed when the front side of the valve disk contacts thevalve seat, and the front flexure plate being axially extendable toaccommodate axial valve disk movement while limiting lateral valve diskmovement.

[0007] According to a further aspect of the invention, there is providedan assembly for supporting an axially movable member, in which theaxially movable member is supported by front and back flexure plates,and the front and back flexure plates are spaced such that each isaxially extended when the other is flat.

[0008] According to a further aspect of the invention, there is providedan assembly for supporting an axially movable member, the assemblycomprising a housing defining a passageway, a support mounted within thehousing, a flexure plate mounted on the support, an axially movablemember secured to the front flexure plate and disposed within thehousing, A compression spring mounted between the support and theaxially movable member to bias the axially movable member in one axialdirection, and the flexure plate being axially extendable to accommodateaxial movement of the axially movable member while limiting lateralmovement of the axially movable member.

[0009] The flexure plates are preferably flat axial springs fabricatedby machining spiral cuts in flat, circular or annular plates. Theflexure plates permit the required axial movement of the valve disk,while sufficiently restricting lateral valve disk movement. Theiroperation is frictionless and they are less expensive to produce than ashaft, bearings and shaft guidance.

[0010] In a further aspect of the invention, different numbers offlexure plates can be used in front and back locations by stacking theflexure plates. Adding more flexure plates will increase the lateralstiffness, as would be required for a heavy valve disk. The number offlexure plates will also affect the axial stiffness and thus the ratingof the required compression spring. Changing the number and shape of thespiral cuts can vary the flexure plates'properties.

[0011] The configuration of the flexure plates can be adjusted bychanging the length of the inner spacer rods relative to the outerspacer rods, which fix the axial distance between the front and backflexure plates. Adjusting the configuration can also be a means ofsizing the axial stiffness of the flexure plate assembly and compressionspring to achieve a wide variety of effective spring stiffnesses asrequired for varying valve opening and closing conditions, i.e. thevalve's dynamic response. The wide available range of closure forcesresult in a valve with faster dynamic response than in the prior art.

[0012] These configurations allow the design of a short, hence morecompact, valve body with a lower non-dimensional pressure losscoefficient than prior art, typically 0.85.

[0013] In a further aspect of the invention, depending on the particularflow conditions, the flexure plates provide sufficient closure force andan axial compression spring is unnecessary.

[0014] These and other aspects of the invention are described in thedetailed description of the invention and claimed in the claims thatfollow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] There will now be described preferred embodiments of theinvention, with reference to the drawings, by way of illustration onlyand not with the intention of limiting the scope of the invention, inwhich like numerals denote like elements and in which:

[0016]FIG. 1. is a side (lateral) view, partly in section, of a valveincorporating improvements according to the invention, with the valveopen;

[0017]FIG. 1A is a detail, partly in section, showing the mounting ofthe flexure plates elements 34 and 42 in FIG. 1, in the valve disksupport housing, element 20 in FIG. 1.

[0018]FIGS. 2A and 2B are respectively axial views showing detail of thefront and back flexure plates, elements 34 and 42 in FIG. 1;

[0019]FIG. 3 is the view shown in FIG. 1, with the valve closed;

[0020]FIG. 4 is a side (lateral) view, partly in section, of a valveincorporating improvements according to the invention, alternativeembodiment, with the valve open; and

[0021]FIG. 5 is the view shown in FIG. 4, with the valve closed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] In this patent document, the word “comprising” is used in itsnon-limiting sense to mean that items following the word in the sentenceare included and that items not specifically mentioned are not excluded.The use of the indefinite article “a” in the claims before an elementmeans that one of the elements is specified, but does not specificallyexclude others of the elements being present, unless the context clearlyrequires that there be one and only one of the elements.

[0023] Referring to the figures, the valve 10 comprises a valve body 12whose interior defines a fluid passageway 14, a valve seat 16 formed onthe valve body 12 in the fluid passageway 14, a valve disk 18, a valvedisk support housing 20, and compression spring 22. The annular spacebetween the housing 20 and the valve body 12 forms a diffuser area 24.The valve disk support housing 20 forms the inner boundary of the flowdiffuser so that fluid pressure loss at the valve seat is partiallyrecovered in accordance with known diffuser principles. Valve disksupport housing 20 is known in the art for check valves, and serves tosupport the valve components within the fluid passageway 14 withoutunduly hindering fluid flow. Normal fluid flow 26 is in the axialdirection 28, and the valve disk 18 moves axially when the valve 10opens or closes. A lateral direction 30 is any direction perpendicularto the axial direction 28. The valve 10 will have other conventionalparts, as is well known to a person in the art. Only features requiredfor an understanding of the invention are shown and described.

[0024] The valve disk support housing 20 is mounted to the inner wall ofthe valve body 14 by struts 32 or other conventional means. The valve 10is preferably made as two separate parts (i.e. the valve body 12 and thedisk support housing 20) to allow easy manufacturing in small sizes, andallow machining of all internal surfaces.

[0025] As illustrated for example in FIG. 1, a front flexure plate 34(FIG. 2A) is mounted to the back, or down stream side, of the valve disk18 by means of a valve disk bolt 36. A back flexure plate 42 (FIG. 2B)is mounted at a fixed distance as determined by the length of the outerspacers 50 so it contacts valve disk support housing 20 at the back ofan annular groove 40 within the valve disk support housing 20. The pairof flexure plates 34 and 42 may be held within an annular groove 40through a lockup ring 54.

[0026] Inner spacer rods 46 are attached to the flexure plates 34, 42,as for example with nuts as shown, near the inner diameters 38, 48 andmaintain a fixed axial distance between the flexure plates' innerdiameters 38, 48. Similarly, outer spacer rods 50 are attached to theflexure plates 34, 42 as for example with a pair of nuts, near theirouter diameters 44, 52 and maintain a fixed axial distance between theouter diameters 44, 52. Referring to FIG. 1A, a lockup ring 54 holds theflexure plates 34, 42 in place in the groove 40 in the valve disksupport housing 20. Alternatively, the front and back flexure plates 34,42 can be mounted in the valve disk support housing 20 by attaching oneor both to the valve disk support housing 20 at the flexure plate outerdiameter or diameters 44, 52. No outer spacer rods 50 are needed if bothflexure plates 34,42 are so attached to the valve disk support housing20

[0027] Both front and back flexure plates 34, 42 are mounted co-axiallywith the valve disk 18 and compression spring 22. Their axis is parallelto the flow direction 26 and axial direction 28. The flexure plates'flat faces, shown in detail in FIG. 2, are therefore perpendicular tothe flow direction 26. The compression spring 22 is located (or mounted)in the hollow center of the flexure plate 42 and abuts against the innerportion of the flexure plate 34. The compression spring 22 is centeredby a circular recess 49 in the valve disk support 20 and by a circularhub 37 in the backside of the front flexure disc 18.

[0028] The flexure plates 34, 42 allow the axial motion of the valvedisk 18 necessary to open and close the valve 10. The flexure plates 34,42 also minimize lateral 30 movement of the valve disk 18 so the valvedisk 18 will align properly with the valve seat 16 when the valve 10closes.

[0029] The flexure plates 34, 42 are preferably flat plates cut fromsheet metal, as shown in FIGS. 2A and 2B. FIGS. 2A and 2B show the frontplate 34 as having a hollow center 56 to accommodate the valve disk bolt36 and the back plate 42 also having a hollow center 58 to accommodatepassage of the compression spring. The back plate 42 can have a solidcenter 58 if no passage for the compression spring 22 or othercomponents is required. The front flexure plate 34 may be attached tothe disk 18 by a valve disk bolt 36 or by other suitable means.

[0030] Referring to FIGS. 2A and 2B, the flexure plate 34, 42 is a flatspring made by machining cuts 60 a, 60 b through the flat plate. Eachcut 60 a, 60 b is along a spiral or spiral-like path from near theflexure plate outer diameter 44, 52 to near the flexure plate innerdiameter 38, 48. The shape of the spiral path is the same (in the figureshown they are the same, this is not necessarily always the case) foreach cut 60 a, 60 b. The spiral cuts are spaced evenly around the plate(in the figure shown they are the same, this is not necessarily alwaysthe case), so the radial angles between the cuts 62 a, 62 b ofcoinciding cuts are equal. The flexure plates 34, 42 can have fewer ormore than the 6 cuts 60 a, 60 b shown. The spiral path shape can bedifferent than that shown, although the path shape should be the samefor all coinciding cuts in front and back flexure plate. At each end ofa cut 60 a, 60 b, a hole 64 a, 66 a, 64 b, 66 b can be cut to relievelocal stresses and facilitate machining the cut 60 a, 60 b. Holes 68 a,68 b, near the inner and outer diameters 38, 48, 44, 52 of the flexureplates 34, 42 may be used for so attaching the flexure plates 34, 42inner and outer spacer rods 46, 50.

[0031]FIG. 1 shows the valve 10 in the open position. The front flexureplate 34 is flat, while the back flexure plate 42 is axially extended bythe differential pressure force across the valve disk overcoming thecompression spring 22 and any spring force in the flexure plates. Theinner spacers 46, being longer relative to the outer spacers 50, forcethe back flexure plate 42 into extension. When fluid flow is normal, theflow creates a differential pressure force across the valve disk 18,which is sufficient to compress the compression spring 22 and extend theback flexure plate 42, maintaining the valve 10 open.

[0032] When the fluid flow decelerates and becomes too low or reverses,it does not produce sufficient differential pressure force across thevalve disk 18 to maintain the valve 10 open. The valve disk 18 thereforemoves axially 28 towards the closed position and seals against the valveseat 16, as shown in FIG. 3. In this closed position, the back flexureplate 42 is now flat, and the front flexure plate 34 is axiallyextended.

[0033] The configuration of the flexure plates 34, 42 can be varied byvarying the lengths of the spacer rods 46 relative to 50 thereby varyingthe flexure plate assembly length, closure force and tilting stiffness.Tilting means rotation of the valve disk about a lateral 30 axis. In theembodiment shown in FIGS. 1 and 3, the inner spacer rods 46 are twicethe length of the outer spacer rods. The outer spacer rods' 50 length isthe same as the distance the valve disk 18 travels as it moves fromfully open to closed.

[0034] A further preferred embodiment is shown in FIGS. 4 and 5, whichshow the valve 10 open and closed respectively. The length of the innerand outer spacer rods 46, 50 and the valve travel distance are allequal. The front and back flexure plates 34, 42 are always identicallyaxially displaced. This embodiment provides for the shortest flexureplate assembly, hence this configuration allows for the design of themost compact valve, at the expense of reduced resistance to preventtilting of the valve disk and increased axial stiffness of the flexureplate assembly.

[0035] A wide range of valve closure forces is available as there areseveral valve components that can be adjusted. The valve closure forcesdepend upon the stiffness of the flexure plates 34, 42, the stiffness ofthe axial spring 22, if any, the configuration of the flexure plates 34,42 and the valve 10 closing travel distance. The opening and closureforces, for the two embodiments can be calculated as follows:

[0036]FIG. 1: Fopen=Fcsc−½Fplate (thus providing, a low opening forcewhile at the same time providing high resistance against tilting of thedisc, which are the two main advantages of this configuration)

[0037]FIG. 3: Fclose=Fcse−½Fplate,

[0038]FIG. 4: Fopen=Fcsc

[0039]FIG. 5: Fclose=Fcse−2Fplate

[0040] Where:

[0041] Fopen=total spring force (flexure plates and compression spring)when valve fully open

[0042] Fclose=total spring force when valve fully closed

[0043] Fcsc=fully compressed compression spring force when the valve isopened

[0044] Fcse=extended compression spring force when the valve is closed

[0045] Fcsc>Fcse

[0046] Fplate=force to fully extend one flexure plate or a stack offlexure plates (front or back) for an assembly where front and backplates are identical (the same plate thickness, and number and shape ofthe spiral cuts).

[0047] Therefore, in these two embodiments, the spring forces aregreater for the valve fully open than for fully closed. The force from aflexure plate or compression spring is proportional to distance it isextended or compressed. Therefore increasing the length of the innerspacer rods 46 relative to the length of the outer spacer rods 50 willincrease the effective closing force exerted by the compression spring22. Conversely, decreasing the length of the inner spacer rods 46relative to the length of the outer spacer rods 50 will decrease theeffective closing force exerted by the compression spring 22.

[0048] In the case of use of front and back guide plates, both guideplates provide lateral support for the valve disk. The inside-diameterspacers distribute the tilting momentum of the disk over the front andback guide plates. Minimum tilting resistance is provided when inner andouter spacer rods have the same length. The longer the relativedifference between inner and outer spacer rods, the larger the tiltingresistance provided by the guide plates. Maximum tilting resistance isachieved when the back flexure plates are flat when the valve is inclosed position.

[0049] This can be achieved at minimum assembly length when the innerspacer rod length (IDL) is twice as long as the outer spacer rod length(ODL) and when the outside diameter spacer length (ODL) is equal to thevalve stroke(s).

[0050] The axial stiffness of the flexure guide plate assembly can bemodified by making the length (IDL) of the inner spacers longer than thelength (ODL) of the outer spacers. The maximum length of the innerspacers is IDL=2×ODL. In this way, two different guide plates can beassembled with minimum (FIGS. 1 and 3) and maximum (FIGS. 4 and 5)lateral stiffness. In FIG. 1, IDL=2×s=2×ODL, so that the total valvestroke requires {fraction (1/4 )} of the load required for theembodiment shown in FIG. 4. In FIG. 4, IDL=1×s=ODL, thus is morecompact.

[0051] A further, preferred embodiment is to stack more than one flexureplate in one or both of the front and back locations 34, 42. Thesestacked plates provide greater lateral stiffness, as would be requiredfor a heavy valve disk.

[0052] In a further preferred embodiment, there is only one flexureplate or stack of flexure plates. If the front flexure plate 34 orplates in the embodiments described above provide or provides forsufficient lateral stiffness and spring forces, no back flexure plate 42is necessary.

[0053] In a further possible embodiment, the valve disk support may belocated upstream of the valve seat, with the valve disk on thedownstream side. In this configuration, the slight axial tension causedby extension of the flexure plate may be used to provide the forces thatbias the valve disk against the valve seat.

[0054] The valve described here may also be operated as a control valvein which the valve opening and closing is controlled externally, and notdependent on fluid flow changes.

[0055] While the flexure plates 34, 42 are shown attached by their outerperipheries to the support housing 20, they could also be attached tothe support housing 20 by their inner portions, for example by a shaftextending from the support housing 20, and the outer periphery of theflexure plate 34 then connected to the outer periphery of the disk 18.

[0056] Further, the use of two flexure plates, one being extended whenthe other is not, and the use of one flexure plate in combination with acompression spring, also has novel application to applications that donot include valves. These embodiments are generally applicable to anyaxially movable member, where axial extension with limited lateralmovement is desirable.

[0057] In the embodiment shown in FIGS. 4 and 5, a wave spring mayadvantageously be used for the compression spring.

[0058] A person skilled in the art could make immaterial changes to theexemplary embodiments described here without departing from the essenceof the invention that is intended to be covered by the scope of theclaims that follow.

I claim:
 1. A valve, comprising: a valve body defining a fluidpassageway, with a valve seat in the fluid passageway; a valve disksupport assembly mounted within the valve body; a front flexure platemounted on the valve disk support assembly; a valve disk secured to thefront flexure plate and disposed within the valve body, the valve diskhaving a front side and a back side, the valve disk being movableaxially within the valve body, the valve being closed when the frontside of the valve disk contacts the valve seat; and the front flexureplate being axially extendable to accommodate axial valve disk movementwhile limiting lateral valve disk movement.
 2. The valve of claim 1 inwhich the valve disk is biased against the valve seat in the absence offlow in the fluid passageway.
 3. The valve of claim 3 further comprisinga back flexure plate mounted on the valve disk support assembly parallelto the front flexure plate, and spaced by spacers from the front flexureplate, the back flexure plate being axially extendable and cooperatingwith the front flexure plate to accommodate axial valve disk movementwhile limiting lateral valve disk movement.
 4. The valve of claim 1 inwhich the front flexure plate comprises a flat disk with spiral cuts. 5.The valve of claim 3 in which each of the front and back flexure platescomprises a flat disk with spiral cuts.
 6. The valve of claim 3 in whichthe back flexure plate has a solid center.
 7. The valve of claim 3 inwhich the front and back flexure plates are spaced such that each isaxially extended when the other is flat.
 8. The valve of claim 3 inwhich the front and back flexure plates are spaced by outer spacer rodsattached near the periphery of the front and back flexure plates.
 9. Thevalve of claim 8 in which the front and back flexure plates are spacedby inner spacer rods attached near inner diameters of the flexureplates.
 10. The valve of claim 9 in which the inner spacers have alength IDL, the outer spacers have a length ODL, the valve disk has astroke s, and IDL=2s=2ODL.
 11. The valve of claim 9 in which the innerspacers have a length IDL, the outer spacers have a length ODL, thevalve disk has a stroke s, and IDL=s=ODL.
 12. The valve of claim 3 inwhich each of the front and back flexure plates are attached at theirrespective peripheries to the valve disk support housing.
 13. The valveof claim 1 further comprising a compression spring mounted co-axiallywith the front flexure plate between the valve disk support housing andfront flexure plate, the compression spring acting to bias the valvedisk against the valve seat.
 14. The valve of claim 3 further comprisinga compression spring mounted co-axially with the front and back flexureplates between the valve disk support and front flexure plate, and thecompression spring passing through the back flexure plate, thecompression spring acting to bias the valve disk against the valve seat.15. The valve of claim 1 further comprising plural flexure platesstacked together with the front flexure plate, each of the pluralflexure plates being axially extendable to accommodate axial valve diskmovement while limiting lateral valve disk movement.
 16. An assembly forsupporting an axially movable member, the assembly comprising: a housingdefining a passageway; a support assembly mounted within the housing; afront flexure plate mounted on the support assembly; a back flexureplate mounted on the support parallel to and spaced from the frontflexure plate by spacer members; an axially movable member secured tothe front flexure plate and disposed within the disk support housing;each of the front flexure plate and back flexure plate being axiallyextendable to accommodate axial movement of the axially movable memberwhile limiting lateral movement of the axially movable member; and thefront and back flexure plates being spaced such that each is axiallyextended when the other is flat.
 17. The assembly of claim 16 in whicheach of the front and back flexure plates comprises a flat disk withspiral cuts.
 18. The assembly of claim 16 further in combination with acompression spring mounted between the support and the axially movablemember to bias the axially movable member in one axial direction.
 19. Anassembly for supporting an axially movable member, the assemblycomprising: a housing defining a passageway; a support mounted withinthe housing; a flexure plate mounted on the support; an axially movablemember secured to the front flexure plate and disposed within thehousing; a compression spring mounted between the support and theaxially movable member to bias the axially movable member in one axialdirection; and the flexure plate being axially extendable to accommodateaxial movement of the axially movable member while limiting lateralmovement of the axially movable member.
 20. The assembly of claim 19 inwhich the flexure plate is a flat disk with spiral grooves.